diff options
author | Sakari Ailus <sakari.ailus@linux.intel.com> | 2018-09-11 05:32:37 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-10-03 17:01:55 -0700 |
commit | ec964c3c00457e7ce6b633a33d1c6b61e0091557 (patch) | |
tree | dceca22439e5501fef1c004bf77cb9cc6d7637ea /drivers/media/v4l2-core/v4l2-fh.c | |
parent | 53819c17ecbee86089396e6e7ae1f3e6de958db9 (diff) |
media: v4l: event: Prevent freeing event subscriptions while accessed
commit ad608fbcf166fec809e402d548761768f602702c upstream.
The event subscriptions are added to the subscribed event list while
holding a spinlock, but that lock is subsequently released while still
accessing the subscription object. This makes it possible to unsubscribe
the event --- and freeing the subscription object's memory --- while
the subscription object is simultaneously accessed.
Prevent this by adding a mutex to serialise the event subscription and
unsubscription. This also gives a guarantee to the callback ops that the
add op has returned before the del op is called.
This change also results in making the elems field less special:
subscriptions are only added to the event list once they are fully
initialised.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: stable@vger.kernel.org # for 4.14 and up
Fixes: c3b5b0241f62 ("V4L/DVB: V4L: Events: Add backend")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media/v4l2-core/v4l2-fh.c')
-rw-r--r-- | drivers/media/v4l2-core/v4l2-fh.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/media/v4l2-core/v4l2-fh.c b/drivers/media/v4l2-core/v4l2-fh.c index c183f0996fa1..0c5e69070586 100644 --- a/drivers/media/v4l2-core/v4l2-fh.c +++ b/drivers/media/v4l2-core/v4l2-fh.c @@ -50,6 +50,7 @@ void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev) INIT_LIST_HEAD(&fh->available); INIT_LIST_HEAD(&fh->subscribed); fh->sequence = -1; + mutex_init(&fh->subscribe_lock); } EXPORT_SYMBOL_GPL(v4l2_fh_init); @@ -95,6 +96,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh) return; v4l_disable_media_source(fh->vdev); v4l2_event_unsubscribe_all(fh); + mutex_destroy(&fh->subscribe_lock); fh->vdev = NULL; } EXPORT_SYMBOL_GPL(v4l2_fh_exit); |